This invention relates to apparatus for detection of selected sound frequency signals emitted by sirens of emergency vehicles or warning signals from vehicles such as trains. The new apparatus may detect a selected sound frequency signal spectrum emitted by various siren or warning sound sources from at least two distinct distances from a sensor to provide a user with a warning of the presence of an emergency vehicle and the relative distance of the emergency vehicle.
Various types of emergency vehicle siren detection systems may be currently known; however, these systems tend to be complicated, elaborate apparatus. The system may involve digital signal processing and programming as part of the detection and differentiation process for detecting sirens of emergency vehicles. There may be a need for a simple, easy to apply siren or warning signal detection system.